Curable compositions comprising polyester resins and styrene have generally been epoxy polyester (vinyl ester) compositions wherein a portion of the polyester is replaced with styrene or other ethylenically unsaturated monomer. See, for example, U.S. Pat. No. 2,691,007, U.S. Pat. No. 3,574,157 and U.S. Pat. No. 3,634,542.
Polyether resin and styrene blends are also known. These blends generally exhibit poor processability, short pot life, high viscosity and cure with conventional curing agents to produce products which do not exhibit good physical properties, such as high heat deflection temperatures and retention of physical properties at elevated temperatures. See, for example, U.S. Pat. No. 2,939,859 directed to a polyepoxide/styrene blend cured with peroxides and/or amines. While the compositions of U.S. Pat. No. 2,939,859 do exhibit a reduction of viscosity over an epoxy composition alone, the resulting products do not exhibit high heat deflection temperatures.
Other patents covering polyepoxide/styrene compositions include U.S. Pat. No. 3,009,898, which are directed to the use of anhydride curing agents, optionally in the presence of a peroxide and/or tertiary amine accelerator.
Epoxy/styrene blends which can be cured with a special curing agent/curing accelerator blend, e.g., an acid anhydride in combination with an onium salt, to yield products which exhibit improved physical properties, especially increased heat deflection temperatures and excellent retention of physical properties at elevated temperatures are disclosed and claimed in U.S. Pat. No. 4,284,753, issued Aug. 18, 1981.
It was discovered that the aromatic monomer (styrene) can be blended with a number of other comonomers in the composition of U.S. Pat. No. 4,284,753 to yield products which exhibit improved physical properties. These compositions are disclosed and claimed in copending patent application Ser. No. 387,998, filed June 14, 1982 now abandoned and refiled on Apr. 9, 1984 as U.S. Ser. No. 598,392.
It has now been discovered that very suitable compositions having excellent chemical and physical properties can be prepared wherein the aromatic monomer is replaced entirely with one or more of the comonomers which were blended with the styrene in the aforementioned copending patent application.